1. Technical Field
Exemplary aspects of the present invention generally relate to a slide rail assembly for use in a cabinet or a drawer, tray, or the like slidably attachable to an image forming apparatus such as a copier, printer, and a facsimile machine; a sheet feeder including the slide rail assembly; and an image forming apparatus including the sheet feeder.
2. Related Art
As illustrated in FIG. 1, one example of a related-art slide rail assembly 101 is constructed of an outer rail 110, an inner rail 120 assembled with the outer rail 110 to be slidably accommodatable within the outer rail 110, an increased diameter roller 103 provided to a downstream end of the inner rail 120 in a direction of accommodation of the inner rail 120 within the outer rail 110 (hereinafter referred to as an accommodation end) to engage between inwardly facing upper and lower edges 111 of the outer rail 110, and a pair of reduced diameter rollers 104 (one of which is shown in FIG. 1) provided to a downstream end of the outer rail 110 in a direction of withdrawal of the inner rail 120 from the outer rail 110 (hereinafter referred to as withdrawal end) to sandwich inwardly facing upper and lower edges 121 of the inner rail 120. A pin shaft 122 is inserted into the increased diameter roller 103 and a pin hole 120a formed in the inner rail 120 so that the increased diameter roller 103 is mounted to the inner rail 120. Similarly, a pin shaft 112 is inserted into each reduced diameter roller 104 and each pin hole 110a formed in the outer rail 110 so that the pair of reduced diameter rollers 104 is mounted to the outer rail 110, respectively.
FIGS. 2A and 2B are schematic views of the related-art slide rail assembly 101, differing in a total length thereof, respectively. Specifically, the total length of the slide rail assembly 101 illustrated in FIG. 2B is longer than the total length of the slide rail assembly 101 illustrated in FIG. 2A. It is to be noted that, for ease of illustration, only one of the reduced diameter rollers 104 is shown in FIGS. 2A and 2B.
As described previously, the related-art slide rail assembly 101 is constructed of two separate rails, that is, the outer rail 110 and the inner rail 120. The inner rail 120 is slidable against the outer rail 110 by a distance identical to total length L1 or L2 of the outer rail 110 illustrated in FIG. 2A or 2B. In other words, the longer the slidable distance of the inner rail 120 against the outer rail 110, the longer the total length L1 or L2 of the outer rail 110, which corresponds to the total length of the slide rail assembly 101 in a state in which the inner rail 120 is accommodated within the outer rail 110. In addition, the longer the slidable distance of the inner rail 120 against the outer rail 110, the longer the distance t1 or t2 between the reduced diameter roller 104 of the outer rail 110, which is a fulcrum of slide movement of the slide rail assembly 101, and an upstream end of the inner rail 120 in the direction of withdrawal of the inner rail 120, that is, the accommodation end of the inner rail 120 to which the increased diameter roller 103 is mounted. Consequently, when the inner rail 120 is withdrawn from the outer rail 110, a load applied to the upstream end of the inner rail 120 increases, thereby possibly breaking the inner rail 120. Thus, insufficient load-bearing capacity of the inner rail 120 limits any increase in the slidable distance of the inner rail 120 against the outer rail 110.
To solve the above-described problem of limited load-bearing capacity, another example of a related-art slide rail assembly 201 is constructed of three separate, telescoping rails as illustrated in FIG. 3. The slide rail assembly 201 includes an outer rail 210, an intermediate rail 220 slidably insertable into the outer rail 210, and an inner rail 230 slidably insertable into the intermediate rail 220. The inner rail 230 carries a drawer, not shown for ease of illustration.
Because the telescopic slide rail assembly 201 is constructed of the three separate rails, a length of each rail can be reduced compared to the slide rail assembly 101, which is constructed of the two separate rails, thereby downsizing the total length of the slide rail assembly 201 in an accommodation state in which both the intermediate rail 220 and the inner rail 230 are accommodated within the outer rail 210. In addition, the shorter length of each rail improves load durability.
However, because the intermediate rail 220, into which the inner rail 230 is inserted, is further inserted into the outer rail 210 in the accommodation state, a height of the slide rail assembly 201 is increased compared to the slide rail assembly 101 constructed of the two rails.